Filter



J. M. LEET Aug. 4, 1953 FILTER Filed July 16, 1949 3nnentor Pf (ttornegs Patentecl Aug. 4, 1953 FIL1ER Jack M. Leet, Flint, Mich., assigner to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application J uly 16, 1949, Serial N 0. 105,088

' 7 Claims. 1

This invention relates to filters and more particularly to a spirally arranged surface filter unit.

The spiral surface filter consists of three basic elements, a filter strip and two annular end plates. The filter strip.is folded over on itself to form a pair of strip parts extending in one direction from the fold. The pair of strip parts are then wrapped in the form of a spiral with the fold at the center of the spiral and with the parts maintained in spaced relation throughout each of the convolutions of the spiral. The edges of the strip are then secured to the end plates and the end portion of the inner part of the strip is secured to the adjacent convolution of the strip. Thus a surface filter with parallel spirally shaped filtering and drainage cavities may be formed from these three basic elements.

The object of the invention is to provide an efiicient and compact surface filter element made of three parts, and having a long spirally shaped filtering passage and an interspaced spirally shaped drainage passage.

Another object of the invention is to form a spiral filter with a spiral filter cavity closed at the inner end for the unfiltered fluid, and an adjacent spiral drainage cavity closed at the outer end for the filtered fluid.

Another object of the invention is to provide a protection strip by extending the spirally wrapped filter strip around the filter unit.

Other objects and advantages Will be apparent from the following description and drawings of the preferred embodiment of the invention.

Figure 1 is a sectional view of the filter.

Figure 2 is a cross section of Figure 1 on the line 2-2.

The filter is mounted in a casing 10 having an inlet fitting 12 secured in an aperture near the upper edge of the casing and a drain plug 14 secured in an opening in the base of the filter. A central post la having a shoulder [8 is secured in an opening in the base of the casing l0. The upper end of the post le extends above the top of the casing ID and has a threaded portion 22 to receive a nut 24 whichsecures the cover 26 to the casing.

Adjacent the lower end of the post [6 a shoulder 28 provides a seat for the seal 30 which has an outwardly extending flange 32 to Support the lower portion of the filter unit. In order to provide an outlet for the filtered fiuid a passage 35 is provided within the post. The passage is threaded at the end 36 of the passage which is concentric with the end of post l6 for connect ing the filter to suitable oi1 piping and at the other end connects with the transverse bore 38 located in the post above the seal 30. The flange 32 on the seal engages the lower edge and pro- Vides a support for the filter unit 48.

At the upper end of the filter unit a seal 42 surrounds the post and has an outwardly extending flange 45 engaging the top of the filter unit. The flange 44 is maintained in contact with the top of the filter unit 40 by a compression spring 46 which is rotatably secured to the nut 24 by having the top turn of the spring fit in a recess 48 in the nut. A by-pass passage is provided in the upper portion of the post [6. The passage consists of a transverse bore 50 located above the seal 42 and a second transverse bore 52 located beneath the seal 42. These transverse ports are connected by an axial passage 54 in which a valve seat 56 is located. A spring loaded hall check valve 58 is provided in the passage 54 t0 engage the seat 56 and maintain the passage closed under normal pressure conditions. However, when the fluid pressure within the casing becomes excessive, the check valve Will open and allow the fluid to by-pass the filter and fiow to the outlet passage 34.

The filter unit 451 has a top plate 60 and a bottom plate 62. These plates are made in annular form to fit the container and may ne secured in spaced relation by a perforated tube 64 closely surrounding the central post i6. The filtering portion of the surface filter element consists of a strip of filter material folded over substantially at the center on itself at 66, and having an inner part 63 and an outer part 'i with the filtering surfaces facing each other. The inner end of the filter strip is preferably secured with a portion of the inner part 68 in contact with the central tube (Mi, and is wound spirally between the plates 60 and 62. The inner part 68 and the outer part m of the filter strip are wound spirally together and are maintained in uniform spaced relation from each other and from the adjacent spiral turns. Thus two separate spiral channels are formed in the filter. The one spiral channel (2 between the parts 68 and 70 of the filter strip forms a channel or passage for the unfiltered fiuid, which contacts the filtering surfaces Which face each other. The filtering fiuid or drainage channel M is located outside of the parts 68 and M, and since the unfiltered oil in the channel 72 tends to compress the drainage channel M, an undulated spacing strap (6, or some equivalent spacing means, is preferably positioned in the drainage channel. The strip cf filtering material is then Wound upon itself a sufficient number of convolutions to provide the desired filter area and sludge space. The outer end 78 of the inner part 68 is secured by gluing or bonding to the adjacent surface of the next inner convolution or spiral turn of the outer part 10. The end of the outer part 80 terminates in spaced relation to the adjacent end 18 of the inner part. The top edges of all the convolutions of the inner part 88 and the outer part M are bonded or glued to the top plate 6E3, and similarly the bottom edges are secured to the bottom plate 62.

The arrangement of the parts 68 and ra of the filter may also be explained as a double spiral of the two strips 58 and 10 with substantially equa1 spacing between the strips and between the turns of the spiral. The spiral space between one pair of opposed faces between the strips is sealed by an integral fold 66 between the inner ends of the parts 68 and 1E3. The other pair of opposed faces are secured together at the outer ends. Thus a double spiral passage is formed With one part I2 for unfiltered fluid closed at the inner end and the other part t l for filtered fluid olosed at the outer end.

Though it is preferable to make the fiuid unit of resin-impregnated filter paper, which is fairly stiff when cured, it will be appreciated that other materials, such as resin-impregnated cloth or wire screen, may be used. Similarly, though it is preferable to form the end plates of fibrous sheet material, they may also ce formed of other suitable sheet materials.

The last convolution of the outer filter part 10 between the end 78 of the inner part and its end does not function as a filter but provides a protective wrapper or cover for the filter unit, in order to prevent damage in shipment, handling and installation. It Will be appreciated that this cover portion may beperforated and secured to the next inner part 53 or fil adiacent the end 18. The unfiltered fluid enters this filter casing through the fitting l2 and surrounds the filter unit ifi in the ccnventional manner. The unfiltered fluid thon passes between the ends 18 and of the inner and outer part respectively and fi.lls the unfiltered fluid channel i2. Filtering then takes place through the entire surface of the filtering strip, the filtered fluid entering the channel Hi throughout its entire length and draining past the folded end 66 of the filter strip part, and through the apertures in the central tube 84. From the cavity within the tube 64 the filtered fluid drains through the outlet passage 34 in the post l6.

It will be appreciated that many modifications of the invention may be made Within the scope of the invention as defined by the appending claims.

I claim:

1. In a filter having a fluid inlet chamber and a fiuid outlet chamber, a pair of filter strips spirally wound with a first passage between said strips and a second passage between the convolutions of said spiral, said inlet chamber being external of said spiral strips, said outlet chamber bein disposed substantially at the center of said spiral, a first sea1 between a first pair of opposed faces of said strips juxtaposed in face to face relation adjacent the center of said spiral, said first passage being defined by said first pair of opposed faces and extending from said first seal to said inlet chamber, and a second seal between a second pair of faces of said strips juxtaposed in face to face relation at the outer end of said spiral, and said second passage being dened by said second pair of opposed faces and extending from said second seal to said outlet chamber.

2. In a filter having a. fluid inlet chamber and a fluid outlet chamber, a pair of substantially parallel filter strips spirally wound with a first passage between said strips and a second passage between the convolutiong of said spiral, said inlet chamber being external of said spiral strips, said outlet chamber being dispcsed substantially at the center of said spiral, a first seal between a first pair of opposed faces of said strips juxtaposed in face to face relation adjacent the center of said spiral, said first passage being defined by said first pair of opposed faces and extending from said first seal to said inlet chamber, a second seal between a second pair of faces of said strips juxtaposed in face to face relationship at the outer end of said spiral, said second pas sage being defined by said second pair of opposed faces and extending from said second seal to said outlet chamber, and means being adapted to commonly seal said passages at the top and bottom edges of said spirally wound strips.

3. In a filter having a fluid inlet chamber and a fluid outlet chamber, a pair of filter strips spirally Wound with a first passage between said strips and a second passage between the convolutions of said spiral, said inlet chamber being external of said spiral strips, said outlet chamber being disposed substantially at the center of said spiral, a first seal between a first pair of opposed faces of said strips juxtaposed in face to face relation adjacent the center of said spiral, said first passage being defined by said first pair of opposed faces and extending from said first seal to said inlet chamber, and a second seal between a second pair of faces of said strips juxtaposed in face to face relation at the outer end of said spiral, said second passage being defined by said second pair of opposed faces and extending from said second seal to said outlet chamber, and one of said strips having one more spiral revolution than the other of said strips between said first and second seals.

4. In a filter having a fiuid inlet chamber and a fluid outlet chamber, a pair of substantially parallel filter strips spirally wound with a first passage between said strips and a second passage between the convolutions of said spiral, said inlet chamber being external of said spiral strips, said outlet chamber being disposed substantially at the center of said spiral, a first seal between a first pair of opposed faces of said strips juxtaposed in face to face relation adjacent the center of said spiral, said first passage being defined by said first pair of opposed faces and extending from said first seal to said inlet chamber, a second seal between a second pair of faces of said strips juxtaposed in face to face relationsliip at the outer end of said spiral, said second passage being defmed by said second pair of opposed faces and extending from said second seal to said outlet chamber, one of said pair of strips having one more spiral revolution than the other of said strips between said first and second seals, and means being adapted to commonly seal said passages at the top and bottom edges of said spirally wound strips.

5 In a filter, a stfip cf filter material, said str1p being folded to form a double strip with a fold between an inner strip portion and an outer str1p portion, said inner and outer strip portions being substantial1y parallel to each other, said strips being spirally wound entirely in one direction with a passage between the parts of said double strip and another passage between convolutions of the Spiral, the free end of the inner strip being secured to the outer surface of the outer strip to provide a seal at the outer end of said spiral, said inner and outer strips being substantially uniformiy spaced from said fold to said sea1, and said inner strip portion being longer than said outer strip portion between said fold and said sea1 by substantially the length of the last revoluticn of said inner strip.

6. In a filter unit, a double layer of fi1ter material, a central tube having an opening in the Wall thereof, said double layer being spirally wrapped in spaced relation entirely in one direction about said tube to provide a pair of channels, the inner ends of both of said layers terminating adjacent said tube, the inner end of the inner layer contacting said tube in tangential relation, the inner end of the outer layer being outwardly spaced from and parallel to said inner end of said inner layer, the inner end of one channel being sealed, and the outer end of the other channel being sealed, one of said layers extending beyond the seal at the outer and of the other channel and surrounding said fi1ter unit to form a protective cover for the filtering portion of the fi1ter.

7. A filter unit as defined in claim 1 and one of said filter strips extending beyond said second sea1 and surrounding said filter unit to form a protective cover for the filtering portion of the filter.

JACK M. LEET.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,693,717 Leinesch Dec. 4, 1928 1,723,053 McKinley Aug. 6, 1929 2,427,862 Judkins Sept. 23, 1947 2,468,862 Briggs May 3, 1949 

